A.C. clutch not engaging or getting power PLEASE HELP!!!!

Hi, I have a 1997 Tacoma 4x4 and my compressor is not getting power. I've checked the fuse and its ok but when I unplug the heater relay with ac switch on (green light lights up on the dash before I pull relay) and test for power there is no power in any of the terminals. could this be a pressure switch? also let me give you a bit more background to my situation, I have replaced the compressor and I pulled a vacuum on the system and when I when to add freon I turned on my ac on full blast and started filling the low pressure with freon. the compressor clutch was not engaged when I started to put freon in the system which is normal from what I've read because there is no pressure in the line and it will engage when you add freon. about 30 seconds into adding freon I hear a drop in rpms and figured the compressor kicked on but it did not and freon began filling up the cab of my truck. I believe I blew my evap coil or something in the dash but that's not my issue, me not getting power to the compressor is my issue. could my pressure switch be bad and that's why the compressor did not kick on when I started to add freon? is there a way to test it with out putting a new evap coil in vacuuming the lines and adding freon with a new one in? cuz I really don't want to do all that for the switch to not be my issue and would like to test the switch before I buy all new stuff. also if the switch is not the issue please let me know what it could be I have absolutely no experience with ac other than changing compressors in a few vehicles.